1. Field
The present invention relates to a light emitting device, and more particularly, to a light emitting device having a wavelength converting layer.
2. Discussion of the Background
Current light emitting diodes (LEDs) can be made to be light in weight, thin in thickness and small in size, and have advantages of energy reduction and long lifetime. Accordingly, the LEDs are used as backlight sources for various types of display devices including cellular phones, and the like. Since an LED package having an LED mounted therein can implement white light having a high color rendering property, it is expected that the LED package will be applied to general illumination while substituting for white light sources such as fluorescent lamps.
Meanwhile, there are various methods of implementing white light using LEDs. Among others, a method is generally used in which white light is implemented by combining an InGaN LED that emits blue light of 430 to 470 nm and a phosphor that can convert the blue light into light with a long wavelength. For example, the white light may be implemented by combining a blue LED and a yellow phosphor excited by the blue LED so as to emit yellow light or by combining a blue LED and green and red phosphors.
Conventionally, white LED packages have been formed by encapsulating an LED chip with a resin containing a phosphor at a package level. However, the phosphor is not uniformly distributed in the resin, and it is difficult to form the resin with a uniform thickness.
Accordingly, studies have been conducted to develop a technique for providing an individual LED chip having a wavelength converting layer with a uniform thickness by forming a uniform phosphor layer at a wafer level or a chip level. The LED chip having the wavelength converting layer with a uniform thickness is provided at the wafer level or the chip level, so that a process of forming the wavelength converting layer can be omitted at a package level. Further, since the wavelength converting layer with the uniform thickness is used, it is possible to prevent color variations which could be generated due to orientation angles.
However, in the technique as described above, the individual LED chip has the wavelength converting layer, so that, when a plurality of LED chips are required, for example, in a high-power LED package, each of the LED chips should be individually mounted and subjected to wire bonding at the package level. Therefore, there is a limitation in simplifying a packaging process. Further, since a plurality of LED chips should be mounted, the size of the package is increased, and it is difficult to provide a light source which may be considered as a point light source.